A. Technical Field
The present invention relates to a production process for a hydroxyalkyl ester, which comprises the step of carrying out a reaction between a carboxylic acid and an alkylene oxide in the presence of a catalyst.
B. Background Art
In a process for producing hydroxyalkyl esters by carrying out a reaction between carboxylic acids and alkylene oxides in the presence of a catalyst, it is necessary to remove heat because the reaction is an exothermic reaction. The removal of the heat is usually carried out indirectly by using a jacket, a coil, and/or a heat exchanger, and streaming cooling water into it. For example, when the removal of the heat is carried out by the heat exchanger, employed is a method which involves circulating a reaction liquid in the outer portion of the heat exchanger to remove heat, and thereafter returning the liquid to the reactor.
However, when the cooling water stops streaming due to power failure, the temperature rises because cooling does not overtake, and an extraordinary reaction acceleratively proceeds accompanying this. Then, there is a possibility that gases are released from a safety valve or a rapture disk because of the extraordinary rise of temperature or pressure.
Then, in the past, the reaction is stopped by cutting the supply of reaction raw materials, and besides, by the following methods: a method which involves ensuring power supply of the cooling water system with backup power supply apparatuses such as a diesel engine; a method which involves replacing the cooling water with other coolants such as industrial water, and ensuring the removal of the heat by streaming the coolant in a separate system with an engine-driving pump; or a method which involves combinations of these methods.
However, it cannot be said that the most favorable method for stopping the reaction is established economically and safely in the presence of a catalyst, a raw acid, a raw alkylene oxide, an aimed product, and a by-product.
Known is a method which involves cooling by adding an inert liquid to the reaction system in order to stop the reaction. However, it is not apparent what a suitable inert liquid is concretely, how this is added thereto, and then, whether the reaction can be stopped safely.
Under higher temperature and pressure, it is known that: the raw alkylene oxide generally produces a glycol by the reaction with water in the presence of an acid, and is exothermically heated. In addition, the glycol exothermically reacts with the alkylene oxide, and the water or glycol cannot easily be used because they are not inactive to the reaction with the raw material.
A. Object of the Invention
In addition, when the raw carboxylic acid includes an unsaturated carboxylic acid such as (meth)acrylic acid, this unsaturated carboxylic acid and a hydroxyalkyl ester as formed are polymerizable substances. Therefore, if the temperature rises, the extraordinary reactions such as these polymerization reactions are promoted, and there is a possibility that the temperature and pressure rise extraordinarily in the reactor. Furthermore, it is worried that the polymerization can be promoted due to the existence of such as water. Accordingly, it cannot be said that the most favorable method for stopping the reaction (such as amount, and temperature) is established in the presence of a catalyst, a raw acid, a raw alkylene oxide, an aimed product, and a by-product.
B. Disclosure of the Invention
The present inventors diligently studied to solve the above-mentioned problems. As a result, they found that the reaction may be stopped by introducing a cool liquid into the reaction system, wherein the cool liquid comprises water in a ratio of not less than 50 weight %, and has a low temperature of xe2x88x925 to 45xc2x0 C.
Accordingly, a production process for a hydroxyalkyl ester, according to the present invention, comprises the step of carrying out a reaction between a carboxylic acid and an alkylene oxide in a reactor in the presence of a catalyst in order to produce the hydroxyalkyl ester, and is characterized in that the reaction is stopped by introducing a reaction terminating liquid into the reactor, wherein the reaction terminating liquid comprises water in a ratio of not less than 50 weight %, and has a low temperature of xe2x88x925 to 45xc2x0 C.
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.